1) Field of the Invention
The present invention relates to a door operating apparatus that opens and closes a door of a vehicle, and more particularly to a door operating apparatus including a detector that detects a rotation by a driving source. The present invention further relates to an electromagnetic clutch that controls a transmission of a driving power, and a coupling mechanism for coupling a movable portion.
2) Description of the Related Art
A door operating apparatus that opens and closes a door of a vehicle generally include a clutch unit that is constituted in an output shaft between a driving motor and a door operating mechanism, in which a door is moved for opening or closing by applying a driving force to the door operating mechanism when the driving motor is driven during ON state of the clutch unit, while the door is manually moved for operating when the clutch unit is turned OFF. The clutch unit is of an electromagnetic type constituted to be turned ON when current is supplied to a coil which is an electromagnetic coil body serving as a clutch driving section, and is constituted to mutually join an armature linked to a driving shaft of the driving motor and a rotor linked to the door operating mechanism by an electromagnetic attracting force to transmit a driving force of the driving motor to the door operating mechanism (see, for example, Japanese Patent Application Laid-Open No. 2003-74255).
There is an operating apparatus that opens and closes a slide door provided on a side of a vehicle main body. The operating apparatus is linked to a driving section, where a driving force of a motor is transmitted to a rotational shaft via a clutch mechanism. The slide door is moved in a sliding manner according to rotation of the rotational shaft. The operating apparatus rotatably supports the rotational shaft to a case. An output gear and a rotor rotated integrally are supported to the rotational shaft in the case. A movable plate that is rotatable relative to the rotational shaft and is engageable with and disengageable from the rotor is supported in the case. An armature is fixed to the movable plate. In the case, an electromagnetic coil body is arranged to face the armature via the rotor to form a magnetic closed loop in cooperation with the armature and the rotor and attract the armature toward the rotor, thereby causing the movable plate to be engaged with the rotor. In the case, a driving device has a rotary sensor that detects rotation of the rotor provided with an annular magnetic member fixedly arranged on an outer peripheral edge of the rotor outside the closed loop and Hall elements facing an outer peripheral face of the magnetic body (see, for example, Japanese Patent Application Laid-Open No. 2000-179233).
As a driving mechanism that opens and closes a slide door provided on a side of a vehicle main body, there is one provided with a reduction gear structure. The reduction gear structure has a worm gear and a worm wheel gear meshing with the worm gear. The worm gear is fixed to an output shaft of a motor. The worm wheel gear is rotatably supported relative to a rotational shaft via a spacer. A disc-like armature made of a magnetic material together with the worm wheel gear is rotatably supported relative to the rotational shaft via the spacer. The armature is supported so as to be movable in an axial direction of the rotational shaft. A disc-like rotor made of a magnetic material is fixed to the rotational shaft. An annular electromagnetic coil member is arranged about the rotational shaft. When current is supplied to the electromagnetic coil member, electromagnetic force attracting the armature toward the rotor is generated. Thus, the armature and the rotor are frictionally engaged with each other. As a result, rotation of the worm gear driven by the motor is transmitted to the rotational shaft via the armature and the rotor rotated together with the worm wheel gear. Thus, the reduction gear structure constitutes the so-called electromagnetic clutch (see, for example, Japanese Patent Application Laid-Open No. 2003-74255).
In the conventional electromagnetic clutch, assuming that an axial direction of the rotational shaft is vertical, the electromagnetic coil member is disposed in a lower region of the rotor, the armature is disposed on an upper face of the rotor, and the worm wheel gear is disposed above the armature. The rotor and the armature have substantially the same outer diameter. The worm wheel gear has an outer diameter smaller than that of the armature. A grease is filled in a space where the worm wheel gear and the worm gear mesh with each other. As described above, in the conventional electromagnetic clutch, however, since the worm wheel gear has an outer diameter smaller than that of the armature, the grease enters between the armature and the rotor via the armature. Thus, sliding occurs in frictional engagement between the armature and the rotor, which hinders transmission of rotation of the worm gear driven by the motor to the rotational shaft. In the conventional electromagnetic clutch, therefore, a disc-like sealing member with a diameter larger than an outer diameter of the armature is interposed between the worm wheel gear and the armature so as to prevent grease from entering in between the armature and the rotor.
There are operating apparatuses that automatically open and close an operating member provided on a rear part of a vehicle. The operating member is a back door of a so-called flip-up type hinge-coupled at an upper and rear portion of the vehicle main body. The operating apparatus constitutes an actuator that opens and closes the back door. The actuator includes a driving unit fixedly provided at a rear pillar of the vehicle main body, an arm rotated integrally with an output shaft of the driving unit, and an elongated rod coupling a distal end of the arm and the back door. A ball joint is employed at a portion connecting the arm and the rod as a coupling mechanism. The ball joint has a ball fixed to the arm and a receiving portion provided on the rod. A clearance between the ball and the receiving portion fitted to each other is filled with highly-viscous grease. The highly-viscous grease prevents swinging of the back door when the back door suddenly moves due to displacement of load acting at a time of opening or closing the back door. A buffer member is interposed so as not to generate noise due to interference of the arm and the rod when the rod is rotated about an axial line extending in a longitudinal direction thereof. The buffer member is provided so as to cover a washer provided on the side of the ball for fixing the ball to the arm (see, for example, Japanese Patent Application Laid-Open No. 2004-44368).
In the operating apparatus provided with the clutch unit in the above manner (see, for example, Japanese Patent Application Laid-Open No. 2003-74255), a stable operation in the door operating mechanism depends on whether a clutch driving section that supports rotation of the output shaft can be firmly held. That is, in order to securely join the armature and the rotor to transmit a rotational force between the both and actuate the operating mechanism, it is necessary to hold the output shaft serving as the rotational shaft for the armature and the rotor along a predetermined axial center securely and it is necessary to firmly hold the clutch driving section serving as a bearing member for the output shaft to the utmost extent. In the conventional technique, therefore, a clutch housing covering one end face and an outer peripheral face of the clutch driving section is provided to a motor bracket covering the output shaft of the driving motor, and the clutch driving section is fixed to one end face of the clutch housing. According to the door operating apparatus thus constituted, since a structure with high strength can be constituted of the motor bracket and the clutch housing, the clutch driving section can be held firmly, and the door operating mechanism can be actuated stably. However, the door operating apparatus provided with the clutch housing together with the motor bracket is considerably disadvantageous regarding its weight, thereby limiting a mounting position therefor.
In the conventional door operating apparatus (see, for example, Japanese Patent Application Laid-Open No. 2000-179233), since a magnetic member is fixedly arranged on an outer peripheral edge of the rotor, the magnetic member is disposed at the outermost peripheral position of the driving section so as to form a large annular shape. The rotary sensor detects rotation of the rotor by the Hall elements facing an outer peripheral face of the magnetic member. In the conventional door operating apparatus, therefore, a distance between the magnetic member and the Hall elements easily fluctuates in the axial direction or a diametrically longitudinal direction of the rotational shaft during rotation of the rotor, which decreases accuracy for detecting rotation of the rotor. In the conventional door operating apparatus, the magnetic member is fixedly arranged on the outer peripheral edge of the rotor outside the closed loop, but the closed loop is formed of the armature and the rotor by the electromagnetic coil member. That is, as long as the magnetic member is provided on the rotor, the magnetic member is positioned so as to be substantially influenced by the closed loop. Accordingly, in the conventional door operating apparatus, magnetic flux from the magnetic member is changed by magnetic closed loop, which deceases accuracy for detecting rotation of the rotor. Furthermore, in the conventional door operating apparatus, a main constitution for the driving section is provided in the case to form a driving unit integrated with the motor and the case is fixed to the body of the vehicle via a bracket. That is, the case is constituted as a metal member having rigidity necessarily. In the conventional driving device, the magnetic member is fixedly disposed on the outer peripheral edge of the rotor and the Hall elements opposed to the outer peripheral face of the magnetic member are provided inside the case, as described above. In the conventional door operating apparatus, therefore, the metal case is made large in a diametrically outward direction of the rotational shaft, which increases the weight of the entire apparatus.
In the conventional electromagnetic clutch (see, for example, Japanese Patent Application Laid-Open No. 2003-74255), since the sealing member only covers an upper face of the armature, when grease reaches below the sealing member, grease cannot be sufficiently prevented from entering in between the armature and the rotor. Since the sealing member is provided as a separate member from the worm wheel gear or the armature, it is difficult to assemble the electromagnetic clutch. In the conventional electromagnetic clutch, since a constitution for preventing grease from entering in between the worm wheel gear and the rotational shaft is not provided, grease enters between the armature and the rotor from a clearance between the worm wheel gear and the rotational shaft via the rotational shaft.
In the conventional coupling mechanism (see, for example, Japanese Patent Application Laid-Open No. 2004-44368), the buffer member interposed between the arm and the rod serves only when the rod is rotated about the axial line and the edge of the receiving portion is forced to come in contact with the washer for the ball. That is, the buffer member does not always serve in a direction in which the arm and the rod are prevented from contacting with each other. Accordingly, since a play in fitting between the ball and the receiving portion is received by only highly-viscous grease, the play in fitting is substantially present. That is, the sudden movement of the back door to swing due to displacement of load acting at a time of opening or closing the back door can be reduced owing to highly-viscous grease, but it is not yet solved.